In theory, this species of Hericium is easy to identify: it is the only North American species that forms a single clump of dangling spines, rather than hanging its spines from a branched structure. Additional identifying features include the fact that it typically appears on the wounds of living or very recently cut hardwoods, and the fact that its spines are mostly more than 1 cm in length.

That's the theory. In practice positive identification is more difficult, since immature specimens of the branched species of Hericium often begin more or less as a single clump, and develop their branches with age. Further confusion stems from the fact that the long-spined species of Hericium, like Hericium erinaceus, may have short spines (1 cm in length or less) when they are young. Microscopic analysis does little to sort things out; micro-details for all four of the North American Hericium species are more or less the same.

In short, you must be sure that your specimen is mature (look for signs of brownish or yellowish discoloration) before betting the house on your identification of Hericium erinaceus--and even then, confusing situations are likely (see the comments in the right-hand column).

Description:

Ecology: Saprobic and parasitic; growing alone; fruiting from the wounds of living hardwoods (especially oaks); late summer and fall (also winter and spring in warmer climates); widely distributed.

Fruiting Body: 8-40 cm across; consisting of one, unbranched clump of 1-6 cm, soft spines hanging from a tough, hidden "base" that is attached to the tree; white, or in age discoloring brownish to yellowish.

To underscore the nightmare that comes with identifying Hericium erinaceus, take a look at these specimens:

. . . which were identified by a prominent mycologist as Hericium erinaceus. However, the photographer, Richard Nadon, noticed that Hericium americanum was growing a few centimeters below the supposed Hericium erinaceus. When he returned at a later date, he found Hericium americanum growing where the "Hericium erinaceus" had been!